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农业面源污染是引发湖泊、河流水域富营养化的一个主要原因,人工湿地被认为是治理农业面源污染的有效措施,但同时存在占地面积大,没有粮食生产力的问题.水稻田作为环境友好的人工湿地生态系统,可以减少流入水体的农业面源污染物.作者通过模拟实验,研究了垄作、平作以及在不同施肥水平下,稻田生态系统对外源污水中N的消纳效果.结果表明:全N(TN)浓度为15 mg/L(其中NH4+-N13.5 mg/L,NO3--N1.5 mg/L)的污水加入3 d后,稻田田面水中NH4+-N浓度平均降低了93%,垄作和平作没有显著差异.各处理NO3--N浓度在灌水后均迅速上升,3 d后达到峰值,平均为9.1 mg/L;7 d后垄作NO3--N浓度平均降至6.8 mg/L,平作为3.5 mg/L;14 d后平均降至1.4 mg/L,不同耕作处理与施肥处理间差异均不显著.田面水中有机氮(ON)含量均在污水加入1 d后达到峰值,完全施肥处理下田面水中有机氮(ON)含量为11.6 mg/L,显著高于减量施肥处理的浓度(4.3 mg/L),说明稻田田面水中的N主要来自施肥.完全施肥处理下田面水中N含量在淹水后的初期高于减量施肥的处理.但两周后肥料处理的差异不显著.说明施肥淹水后的前两周对控制流入水体的N是关键时期.研究表明利用稻田生态系统在1周以内就可以有效控制污水中的无机态N.
Agricultural non-point source pollution is one of the main causes of eutrophication in lakes and rivers. Constructed wetlands are considered as effective measures to control agricultural non-point source pollution, but at the same time there is a problem of large land occupation and lack of food productivity. Friendly artificial wetland ecosystem can reduce the agricultural non-point source pollutants flowing into the water body.The author studied the effects of ridge-cropping, flat-planting and paddy field ecosystem on N removal from the exogenous wastewater by simulating experiments.The results showed that After 3 days of adding TN (15 mg / L), NH4 + -N (NH4 + -N13.5 mg / L and NO3 - N1.5 mg / L) 93%, there was no significant difference between the two crops. The concentrations of NO3 - N in all treatments increased rapidly after irrigation and reached an average of 9.1 mg / L after 3 d, and the average NO3 - N concentration decreased to 6.8 after 7 d mg / L, the average level was 3.5 mg / L, and the average was 1.4 mg / L after 14 days.The differences between different tillage treatments and fertilization treatments were not significant.The organic nitrogen (ON) The organic nitrogen (ON) content in surface water was 11.6 mg / L under high and complete fertilization treatments, which was significantly higher (4.3 mg / L), indicating that N in paddy field surface water mainly comes from fertilization.The content of N in surface water of paddy field is higher than that of decreasing fertilization at the early stage after flooding.But two weeks later, the content of fertilizers The difference was not significant, indicating that the first two weeks after fertigation was critical to control N inflow, and the results showed that the use of paddy ecosystem within one week can effectively control the inorganic N in sewage.